Reaction of 2‐Phenyl‐4‐arylidene‐1,3‐oxazolones with Different Nucleophiles for Synthesis of Some New Heterocycles

Refluxing of 1,3‐oxazolone ( 1a ) with malononitrile in dry benzene and in the presence of ammonium acetate afforded imidazolone derivative ( 2 ). However, carrying out the same reaction in absolute ethanol and in the presence of piperidine as a base gave the benzamide derivative ( 4 ). Fusion of ( 1a ) with p‐anisidine gave the open adduct benzamide ( 6 ), which cyclized in acidic medium to give imidazolone derivative ( 7 ). Heating of imidazolone ( 7 ) with malononitrile above its melting point afforded 1,3‐diazepine derivative ( 8 ). Reaction of the carbohydrazide ( 9 ) with isatin in ethanol gives the corresponding Schiff base ( 11 ), which then reacted with acetyl acetone, ethyl acetoacetate, ethyl cyanoacetate, and malononitrile in n‐butanol and piperidine to afford benzamide derivative ( 13 , 14 , 15 ) and ( 16 ), respectively. The structures of the newly synthesized compounds were established on the basis of IR, ¹H‐NMR, mass spectra, and elemental analyses.